The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also be inventions.
Total hip replacement refers to a surgical procedure where a hip joint is replaced using a prosthetic implant. There are several different techniques that may be used, but all include a step of inserting an acetabular component into the acetabulum and positioning it correctly in three dimensions (along an X, Y, and Z axis).
In total hip replacement (THR) procedures there are advantages to patient outcome when the procedure is performed by a surgeon specializing in these procedures. Patients of surgeons who do not perform as many procedures can have increased risks of complications, particularly of complications arising from incorrect placement and positioning of the acetabular component.
The incorrect placement and positioning may arise even when the surgeon understood and intended the acetabular component to be inserted and positioned correctly. This is true because in some techniques, the tools for actually installing the acetabular component are crude and provide an imprecise, unpredictable coarse positioning outcome.
It is known in some techniques to employ automated and/or computer-assisted navigation tools, for example, x-ray fluoroscopy or computer guidance systems. There are computer assisted surgery techniques that can help the surgeon in determining the correct orientation and placement of the acetabular component. However, current technology provides that at some point the surgeon is required to employ a hammer/mallet to physically strike a pin or alignment rod. The amount of force applied and the location of the application of the force are variables that have not been controlled by these navigation tools. Thus even when the acetabular component is properly positioned and oriented, when actually impacting the acetabular component into place the actual location and orientation can differ from the intended optimum location and orientation. In some cases the tools used can be used to determine that there is, in fact, some difference in the location and/or orientation. However, once again the surgeon must employ an impacting tool (e.g., the hammer/mallet) to strike the pin or alignment rod to attempt an adjustment. However the resulting location and orientation of the acetabular component after the adjustment may not be, in fact, the desired location and/or orientation. The more familiar that the surgeon is with the use and application of these adjustment tools can reduce the risk to a patient from a less preferred location or orientation. In some circumstances, quite large impacting forces are applied to the prosthesis by the mallet striking the rod; these forces make fine tuning difficult at best and there is risk of fracturing and/or shattering the acetabulum during these impacting steps.
Some prosthetic implants implement a modular paradigm in which a surgeon constructs a prosthesis for implant. Often two or prosthetic components are assembled at a time of installation. It is common for such modular systems to define a mechanical interface between the prosthetic components and the surgeon uses the interface when constructing the prosthetic assembly for implant. The mechanical interface may include, for example, use of machine taper standards including Morse tapers and the like.
In these machine tapers, a male member includes a generally conical form (i.e., tapered) that fits into a female socket which has a matching complementary taper that is intended to match the taper of the male form.
A mechanical interface for components of a prosthetic assembly may use such machine tapers. For example, a femoral prosthesis used in total hip replacement procedures may include a femoral stem that is installed into an end of a femur and then a femoral head is installed onto an exposed end of the femoral stem using a machine taper. Currently the procedure for installing the femoral head includes the surgeon using a mallet or tamp to drive the femoral head onto the exposed end of the femoral stem.
A surgeon may desire that the head be accurately installed onto the stem as complications from installation of a misaligned prosthetic assembly may occur. Errors in installation of the head onto the stem may occur from any of a number of potential causes, including a mismatch of the complementary tapers and incorrect seating of the head onto the stem caused by the surgeon's use of a mallet to strike and drive the head onto the stem. It is possible that misalignments that may not be visually apparent to the surgeon could lead to one or more complications.
What is needed is a system and method for allowing any surgeon, including those surgeons who perform a fewer number of a prosthetic assemblies as compared to a more experienced surgeon who performs a greater number of procedures, to provide an improved likelihood of a favorable outcome approaching, if not exceeding, a likelihood of a favorable outcome as performed by a very experienced surgeon with the replacement procedure such as, for example, improving real-time on-site construction of a prosthetic assembly to be used in a prosthetic installation on an actual patient.